1. Field of the Invention
This invention pertains to tubes having specially configured internal walls, through which a fluid may move with improved efficiency, and more particularly, to such tubes that channel gases, and articles suspended in a gas flow, centrally or axially down the tube. In a particular aspect, this invention provides sound absorbing tubes that both improve gas flow and function to reduce the noise emanating from engines, firearms and the like. This invention also concerns surfaces that incorporate aspects of the specially configured internal walls of those tubes that improve the flow characteristics over the surfaces to produce beneficial results.
2. Discussion of the State of the Art
Backpressure in engine exhausts is a well-known phenomenon that robs energy from the engine. Mufflers and catalytic converters contribute to the backpressure because current designs typically require engine exhaust gases to pass through geometry changes caused by baffles. It is a primary object of the present invention to provide a tube functional as an engine exhaust conduit and as a sound absorbing muffler that reduces backpressure and reduces and ameliorates exhaust noise.
More generally, other tubular devices known in the art rely on fluid flow optimization and require noise moderation, mufflers being one example. Other examples where fluid flow within a tube requires noise moderation include, but are not limited to, firearms (shock waves in firearm barrels reduce the kinetic energy of projectile fired and cause extreme noise), and jet engine exhaust (suppression of jet engine noise has long been a problem).
Fluid flow over surfaces can also cause drag and inefficiency, for example in projectile flight (drag on projectile reduces range and may destabilize flight), aircraft wings and other airfoils (drag reduces efficiency and turbulence may adversely impact lift generated by an airfoil), terrestrial vehicles (drag reduces efficiency), and drag from fluid flows around jet engine nacelles reduces efficiency). What is needed is a way to reduce deleterious effects of turbulence and shock waves in systems relying on fluid flows, to improve the efficiency or effectiveness of those systems.
Seemingly, a principle in the operation of prior art devices such as mufflers and firearm silencer/suppressors that sought to minimize or eliminate is noise was the notion that noise and turbulence in a fluid stream represent disadvantageous and spurious factors that must be cancelled or otherwise eliminated. Consequently, engine mufflers which sought largely to minimize the noise of internal combustion engine exhaust were typically designed with various types of baffles that hindered flow and noise cancellation chambers or structures that were designed to effect dissipation strategies. Firearm silencer/suppressors likewise sought to accomplish the noise reduction task directly by deflecting the explosive stream into dead end chambers or by turning the noise energy back on itself to produce cancellation effects.
Such thinking has produced a body of muffler prior art where the flow of exhaust gases is seldom if ever left unobstructed and is required to navigate a tortuous geometric path as the gas proceeds from inlet or entry port to exhaust or outlet port. Such noise cancellation strategy also persists in prior art technologies that seek to address the noise suppression that is sought to be achieved in firearm silencer/suppressors. Whereas, by definition, a firearm silencer/suppressor must generally leave an unobstructed path through which the bullet can pass within the silencer-suppressor after it leaves the gun barrel (some have bullet-penetrable “wipes” of rubber, plastic or foam), the emphasis in the prior art has stressed providing dead end “expansion” chambers and baffles that seek to turn the noise and other unwanted energy as well as some of the flow back on itself to cancel the explosive report. For example, a search on Google for silencer/suppressors yielded, among other things, images of literally hundreds of firearm silencer/suppressors including sectional views. The great majority of structures seem to involve baffles that are either perpendicular to or are inclined toward the bullet's path coupled with ports to dead end expansion chambers in contrast to the designs disclosed in this application
The intent of the instant inventor has been to organize or “manage” the noise, turbulence, and gas flow in both mufflers and firearm silencer/suppressors as well as in other tubular applications as disclosed herein. A flow tube can provide superior noise suppression and improve performance of the underlying function of assisting flow by employing a “waveguide” or “flow guide” construction according to this invention. Specifically, engine mufflers of this invention not only reduce engine exhaust noise, but also reduce the back pressure that prior art mufflers typically impose on the engine to which they are attached. Firearm silencer/suppressors disclosed herein not only successfully moderate the report of a firearm, but also can incrementally increase range and accuracy. Aircraft engine noise suppressors can improve thrust marginally. And surfaces incorporating the principles of this invention can reduce fluid drag, thereby improving efficiency. Hence there are created flow tubes that both absorb and suppress noise while assisting with flow and surfaces that assist with the efficiency of flow.